1. Field of the Invention
The present invention relates to a bulk data transmission system and, more particularly, to a bulk data transmission system for allowing data terminals to interchange a great amount of serial data by distributing them to a plurality of communication paths.
2. Description of the Prior Art
A conventional bulk data transmission system of the type described uses packets. For example, a basic interface prescribed by CCITT Recommendations, I Series is capable of transmitting two B channels (64 kbps) and a single D channel (16 kbps) at a symbol rate of 192 kbps. Assume that a data terminal capable of transmitting data at a rate of 128 kbps sends data via such a basic interface. Then, it is necessary to transform 128 kbps data to be transmitted to two parallel data sequences each having a rate of 64 kbps and send each data sequence over respective one of the two B channels (B1 and B2). Generally, since the two B channels are each routed through a different communication path, a time gap occurs between the B channels. In addition, the receiving station cannot determine which of the two parallel data sequences corresponds to the channel B1 (or B2) of the transmitting section. Therefore, when the two parallel data sequences are simply transmitted over the two B channels at the same time, the original 128 kbps data cannot be reproduced at the receiving station. By contrast, when the data are transmitted in packets, the receiving station can reproduce the original data by referencing packet numbers included in headers each being added to a particular packet.
However, a problem with the conventional packet type bulk data transmission system is that since the maximum packet length is limited, it is necessary to assemble and then disassemble a great number of packets at the cost of time. This is especially true when a great amount of data is transmitted. Moreover, the headers added to the individual packets degrade the efficient use of bits by data to be transmitted.